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| 型号： | MIC3201YME |
| 厂商： | Micrel Inc |
| 文件页数： | 9/16页 |
| 文件大小： | 0K |
| 描述： | IC LED DRIVER 8ESOIC |
| 特色产品： | MIC3201 High Brightness LED Driver |
| 标准包装： | 95 |
| 恒定电流： | 是 |
| 拓扑： | PWM，降压（降压） |
| 输出数： | 1 |
| 内部驱动器： | 是 |
| 类型 - 主要： | 通用 |
| 类型 - 次要： | 高亮度 LED（HBLED） |
| 频率： | 1MHz |
| 电源电压： | 6 V ~ 20 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm Width）裸露焊盘 |
| 供应商设备封装： | 8-SOIC-EP |
| 包装： | 管件 |
| 工作温度： | -40°C ~ 85°C |
| 其它名称： | 576-3659-5 MIC3201YME-ND |
V L = L
V CS ( MAX ) ? V CS ( MIN )
t r = L
t f = L
T = t r + t f , F SW =
Micrel, Inc.
Application Information
The MIC3201 is a hysteretic step-down constant-current
High-Brightness LED (HB LED) driver. The internal block
diagram is shown in Figure 1. The MIC3201 is
composed of a current sense comparator, voltage and
current reference, 5V regulator, MOSFET driver, and a
MOSFET. Hysteretic mode control, also called bang-
bang control, is the topology that does not employ an
error amplifier, and instead uses an error comparator.
The inductor current is controlled within a hysteretic
window. If the inductor current is too small, the power
MOSFET is turned on; if the inductor current is large
enough, the power MOSFET is turned off. It is a simple
control scheme with no oscillator and no loop
compensation. Since the control scheme does not need
loop compensation, it makes a design easy, and avoids
problems of instability.
Transient response to load and line variation is very fast
and only depends on propagation delay. This makes the
control scheme very popular for certain applications.
LED Current and R CS
The main feature in MIC3201 is to control the LED
current accurately within ± 5% of set current. Choosing a
high-side R CS resistor helps for setting constant LED
current irrespective of wide input voltage range. The
following equation gives the R CS value:
MIC3201
Frequency of Operation
To calculate the frequency spread across input supply:
dI
dt
L is the inductance, dI is fixed (the value of the hysteresis)
dI =
R CS
V L voltage across inductor L which varies by supply.
For current rising (MOSFET is ON):
dI
V L _ RISE
where:
V L_RISE = V IN – I LED ·R CS - V LED
For current falling (MOSFET is OFF):
dI
V L _ FALL
where:
V L_FALL = V D + I LED ·R CS + V LED
1
T
R CS =
2 I LED
(
1 V CS( MAX ) + V CS( MIN)
)
F SW =
(V D + I LED ? R CS + V LED ) ? (V IN ? I LED ? R CS ? V LED )
L ? dI ? ( V D + V IN )
R CS ( ? )
ILED (A)
I 2 R (W)
Size (SMD)
Where
V D is Schottky diode forward drop
2.00
1.00
0.63
0.56
0.50
0.40
0.33
0.28
0.24
0.22
0.20
0.1
0.2
0.3
0.35
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0.0200
0.0400
0.0567
0.0691
0.0800
0.1000
0.1188
0.1372
0.1536
0.1782
0.2000
0402
0402
0402
0603
0603
0805
0805
0805
0805
0805
1206
V LED is total LEDs voltage drop
V IN is input voltage
I LED is average LED current:
According to the above equation, choose the inductor to make
the operating frequency no higher than 1MHz.
Free Wheeling Diode
The free wheeling diode should have the reverse voltage
rating to accommodate the maximum input voltage. The
forward voltage drop should be small to get the lowest
conduction dissipation for high efficiency. The forward current
rating has to be at least equal to LED current. A Schottky
diode is recommended.
LED Ripple Current
Table 1. Selecting R CS for LED Current
The LED current is the same as inductor current. If LED ripple
current needs to be reduced then place a 10μF capacitor
For V CS(MAX) and
characteristic table.
V CS(MIN) refer
to
the
electrical
across LED.
February 2011
9
M9999-021011-B
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC3201YME EV | 制造商:Micrel Inc 功能描述: |
| MIC3201YME TR | 功能描述:LED照明驱动器 HBLED Driver with High-Side Current Sense RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| MIC3202 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:High-Brightness LED Driver with Integrated MOSFET and High-Side Current Sense |
| MIC3202-1 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:High-Brightness LED Driver with Integrated MOSFET and High-Side Current Sense |
| MIC3202-1YME | 功能描述:LED照明驱动器 37V/ 1A HBLED Driver with High-Side Current Sense RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
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